Created attachment 1065220 [details]
Patched file

Description of problem:
I have this wifi USB dongle: AVM FRITZ!WLAN USB Stick N v2 (https://wikidevi.com/wiki/AVM_FRITZ!WLAN_USB_Stick_N_v2)

It is first recognised by the system as a USB CD-ROM (CD-ROM mode) and switch (once the CD is ejected) to WiFi mode. This works on Debian Wheezy on my Raspberry Pi, but does not work on Fedora 22 on my laptop. On Fedora 22, the stick is stuck in CD-ROM mode, no USB CDROM is visible and it can't be ejected.

I've upgraded to Debian Jessie on my RPi and I have the same problem as on Fedora 22.

In journalctl on Fedora, it was reporting "usb_modeswitch: use overriding config file /etc/usb_modeswitch.d/057c:62ff; make sure this is intended". Which made me investigate the usb_modeswitch path. Indeed this file was matching the vendor and product ID of the stick in CD-ROM mode. On Debian Jessie, this file does not exist (and journalctl does not provide any helpful hints).

I found 2 interesting things on Fedora:
  1. removing the file /etc/usb_modeswitch.d/057c:62ff make the device mountable as a cdrom. Once ejected, it switch automatically to WiFi mode.
  2. even better, by adding one line to this file, I made it work (i.-e. I plug the stick and it switch automatically to WiFi mode). The new line is (without the single quotes): 'MessageContent="5553424312345678000000000000061b000000ff0000000000000000000000"'

I've found this line in the following file: http://www.draisberghof.de/usb_modeswitch/device_reference.txt
But I have no clue what it means.

When I copied the modified file to Debian Jessie, suddenly it was working there too.


Version-Release number of selected component (if applicable):
WiFi USB dongle: AVM GmbH FRITZ WLAN N v2 [RT5572/rt2870.bin]

On Fedora 22:
usb_modeswitch: 2.2.1-1.fc22
usb_modeswitch-data: 20150115-1.fc22
Kernel: 4.1.4-200.fc22.x86_64

On Debian Jessie:
usb_modeswitch: 2.2.0+repack0-2
usb_modeswitch-data: 20150115-1
Kernel: 4.1.6-v7+



How reproducible:
All the time.


Steps to Reproduce:
1. Require the specific hardware and plug it;
2. Nothing happens: no cdrom and no wifi
3. Journalctl reports the warning about the overriden config file in /etc

Actual results:
As I said in step 2: nothing happens, no wifi and no cd

Expected results:
The best is: WiFi device is available.
Or at least that the stick is able to be ejected as a CD to allow it to switch mode.

Additional info:
As said in the description, by adding this magic line, the best solution is working!